Protecting the Honor of Shabbos

The Chofetz Chaim, zt”l, advocated protesting against flagrant Shabbos violation in his times. Nevertheless, he had certain general rules that he followed to ensure that his rebukes were as effective as possible. The first rule was to avoid protesting on Shabbos itself. He explained that while Jews are involved in sinning it is much more difficult to convince them to change. As the Mishnah famously states in Avos: "עבירה גוררת עבירה"—“One sin draws another in its wake.” When Jews are involved in sin, they find it much easier to sin again by disregarding the protestor—or worse, by falling into outright sinful behavior to retaliate. And the Chofetz Chaim would say that the inverse also holds true. The Chofetz Chaim would tell those who went around selling his sefarim to bring them to shuls after davening. He reasoned that after having davened with a minyan, people would be much more likely to do the mitzvah of purchasing a sefer on guarding their speech.
Not surprisingly, the Shabbos protests lodged by the Chofetz Chaim were very effective. On one occasion, he went to a certain city with his brother-in-law to raise money for the yeshiva in Radin. When he heard that the Jews there did not keep Shabbos he wanted to leave immediately, but the locals begged him to remain so as not to shame their city. Instead of asking for donations from money tainted by chilul Shabbos, the Chofetz Chaim stayed a couple of weeks and gave three fiery derashos for the thousands of Jewish residents. In each of them he discussed the terrible ills of chilul Shabbos and the vast spiritual attainments of keeping Shabbos.
Later, when the Chofetz Chaim recounted this story to his son, he remarked, “Boruch Hashem, as a result of those derashos, three hundred stores closed for Shabbos! When people heard about this it made a great kiddush Hashem.”